This invention relates to mining operations and more particularly concerns a method and machine for removing blockage and silt preparatory to mining a portion of the remaining ore at a mining site, or preparatory to the placement of explosive charges in an auger hole for reclammation purposes.
Auger type surface mining has been employed extensively in recent years at locations where overburden removal costs or other considerations preclude further surface mining. Since auger mining severely undermines support for the overburden, further blasting for overburden removal in augered zones produces contaminated ore. Even at mining sites in which technological improvements have reduced the contaminates produced, the danger associated with additional blasting in augered zones because of the collapse of the overburden precludes further surface mining. For these reasons, augered seams have simply been abandoned and when not required by law, left without reclamation. Recent statutes have, however, required that auger holes be covered to reduce hazards to children.
Weathering causes abandoned seams to undergo detrimental changes. For example, the exposed highwall deteriorates and fragments above the auger hole which causes sloughing. The sloughing generally contains large rocks, decomposed shale and eroded surface soil which accumulate at the base of the highwall and at times spill into and seal the mouth of the holes. Since coal is generally found between deposits of shale and sandstone, it often occurs proximate ground water. This ground water fills the auger holes which are impounded by the sloughing and deposits slit by a precipitus action. The silt is deposited adjacent the highwall side of the water impoundments and at low points along the length of the auger holes. This siltation tends to build rapidly and may partially fill up to 30 lineal feet of the auger hole in a period of ten years. Further, the siltation continues to accumulate until the auger hole is completely filled. Recent developments in mining and demolition have enabled further mining of existing auger holes, but applications of this new technology is contingent upon certain specifc auger hole environment conditions. In order to extract commerically saleable ore from the previously mined auger holes, the ore must be relatively free of contaminates. Additionally, access to the holes must be readily available. Accordingly, it is necessary to have a relatively clean auger hole environment in order to produce saleable ore from the pre-existing holes.
In blasting mining operations, access and hole size consistency are important for the physical sizing and deployment of the charges. In this connnection, it is necessary to develop commerically feasible methods for removing blockage and contaminates from auger holes which may have been worn during the mining operation into elliptical cross-sectional configurations, especially at the entry of the holes. Further, statuatory and safety restrictions prevent persons from entering the auger holes thereby necessitating a method for cleaning the auger hole which can be operated from a location remote from the hole confines.